SELECT MAX MySQL查询 - 异常结果

My guess is that animal_id is being stored as a character field rather than as a numeric field. If you want the numeric max, try this:

select max(animal_id + 0)
from info_table

When you add two values together in MySQL and one is a character string, then the initial numeric characters (if any) are converted to a number.

Judging by the sample data in your other columns, you have made all your columns of type VarChar, i.e. text. The "anomalous result" you are seeing is one of the many reasons this is a bad idea.

Sorting a series of strings will generally be done in "alphabetical", or "lexical" order - "b" comes before "z", but not before "aaa". Strings consisting entirely of digits may look like numbers, but they will sort like any other string - so "1" comes before "2", but so does any string beginning with "1", such as "1a", "10", "100". This is generally not what you want.

Rather than working around this and the other problems you will encounter with, e.g. date fields, always set your tables up with correct types on every column.